Microhabitat location and niche segregation in two sibling species of Drosophilid parasitoids: Asobara tabida (Nees) and A. rufescens (Foerster) (Braconidae: Alysiinae)

Abstract

Olfactometer tests with Asobara tabida (Nees 1834), a larval endo-parasitoid of frugivorous Drosophilidae showed that females are attracted to the odour of host food: a suspension of living yeast. This attraction decreased as the fermenting medium grew older and became less likely to contain suitable host stages. Olfactometer tests with - what was considered to be - A. tabida from two different microhabitats (fermenting fruits and decaying plants) showed a genetically determined difference in microhabitat odour preference between the two microhabitat 'strains'. Each 'strain' preferred the odour of its own microhabitat. This odour preference was not modified by larval conditioning. Hybridization tests indicated that we were dealing with two sibling species: A. tabida and A. rufescens (Foerster 1862), reproductively isolated by a pre-mating isolation mechanism only. Enforced matings resulted in fertile female offspring. Some small morphological differences were detected. The two species live sympatrically, although each inhabits and is most attracted to its own microhabitat.

Combining geometric morphometrics with pattern recognition for the investigation of species complexes

“…Hymenopteran parasitoids are a highly speciose group whose species are generally characterized by high levels of host specificity and low levels of morphological differentiation (Unruh & Messing, 1993; Polaszek & Dessart, 1996; Claridge, Dawah & Wilson, 1997). Such a combination of characteristics explains the frequency of unsolved species complexes within the Hymenoptera (Vet et al ., 1984a,b; Pungerl, 1986; Polaszek & Walker, 1991; Polaszek, Ubeku & Bosque‐Perez, 1993; Fernando & Walter, 1997). Many traditional taxonomic investigations group hidden species within a single taxon.…”

Capacity of Japanese Asobara species (Hymenoptera; Braconidae) to parasitize a fruit pest Drosophila suzukii (Diptera; Drosophilidae)

“…Japanese specimens of these two species were identified and discriminated by the shapes of third and fourth segments of antenna and basitarsus of hind leg that were firstly found to discriminate European specimens of these species (Vet et al. ). The present study revealed that individuals of A .…”

“…), although some have been recorded from fungivorous, tree‐sap feeding and herbage‐feeding drosophilid flies and also from some flies of the family Tephritidae (Vet et al. ; Fischer ; Driessen et al. ; Ovruski et al.…”

Host-associated volatiles attract parasitoids of a native solitary bee, Osmia lignaria Say (Hymenoptera, Megachilidae)

“…Parasitoids use a variety of chemical cues to identify and locate potential hosts, including those emitted by the host's habitat (Vet et al 1984), host byproducts (i.e. frass, Agelopoulos et al 1995), organisms living in association with the host (Sullivan et al 2000), and the host itself (Wiskerke et al 1992, Jumean et al 2009).…”